package net.kehuilai.util;

import java.security.MessageDigest;
import java.util.Random;

/**
 * Created by genghz on 16/12/9.
 */
public class StringTool {

    private static final String[] hexDigits = {"0", "1", "2", "3", "4", "5", "6", "7",
            "8", "9", "a", "b", "c", "d", "e", "f"};

    private static final String baseStr = "abcdefghijklmnopqrstuvwxyz0123456789";

    public static boolean isEmpty(String orig){
        return orig == null || orig.equals("");
    }

    public static String formatString(String format, Object... arguments) {
        return String.format(format.replaceAll("\\{\\}", "%s"), arguments);
    }

    public static String md5(String origin) {
        String resultString = null;
        try {
            resultString = origin;
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(resultString.getBytes("UTF-8"));
            resultString = byteArrayToHexString(md.digest());
        } catch (Exception ignore) {
        }
        return resultString;
    }

    public static String getRandomStr(int length) {
        Random random = new Random();
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < length; i++) {
            int number = random.nextInt(baseStr.length());
            sb.append(baseStr.charAt(number));
        }
        return sb.toString();
    }

    private static String byteArrayToHexString(byte[] b) {
        StringBuilder resultSb = new StringBuilder();
        for (byte aB : b) {
            resultSb.append(byteToHexString(aB));
        }
        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n = 256 + n;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }
}
